The present invention relates to ink containers for providing ink to inkjet printers. More specifically, the present invention relates to ink containers that make use of a network of heat bonded fibers for retaining and providing the controlled release of ink from the ink container.
Inkjet printers frequently make use of an inkjet printhead mounted within a carriage that is moved back and forth across print media, such as paper. As the printhead is moved across the print media, a control system activates the printhead to deposit or eject ink droplets onto the print media to form images and text. Ink is provided to the printhead by a supply of ink that is either carried by the carriage or mounted to the printing system not to move with the carriage.
For the case where the ink supply is not carried with the carriage, the ink supply can be in continuous fluid communication with the printhead by the use of a conduit to replenish the printhead continuously. Alternatively, the printhead can be intermittently connected with the ink supply by positioning the printhead proximate to a filling station that facilitates connection of the printhead to the ink supply.
For the case where the ink supply is carried with the carriage, ink supply may be integral with the printhead, whereupon the entire printhead and ink supply is replaced when ink is exhausted. Alternatively, the ink supply can be carried with the carriage and be separately replaceable from the printhead. For the case where the ink supply is separately replaceable, the ink supply is replaced when exhausted, and the printhead is replaced at the end of printhead life. Regardless of where the ink supply is located within the printing system, it is critical that the ink supply provide a reliable supply of ink to the inkjet printhead.
In addition to providing ink to the inkjet printhead, the ink supply frequently provides additional functions within the printing system, such as maintaining a negative pressure, frequently referred to as a backpressure, within the ink supply and inkjet printhead. This negative pressure must be sufficient so that a head pressure associated with the ink supply is kept at a value that is lower than the atmospheric pressure to prevent leakage of ink from either the ink supply or the inkjet printhead frequently referred to as drooling. The ink supply is required to provide a negative pressure or back pressure over a wide range of temperatures and atmospheric pressures in which the inkjet printer experiences in storage and operation.
One negative pressure generating mechanism that has previously been used is a porous member, such as an ink absorbing member, which generates a capillary force. Once such ink absorbing member is a reticulated polyurethane foam which is discussed in U.S. Pat. No. 4,771,295, entitled xe2x80x9cThermal Inkjet Pen Body Construction Having Improved Ink Storage and Feed Capabilityxe2x80x9d to Baker, et al., issued Sep. 13, 1988, and assigned to the assignee of the present invention.
There is an ever present need for ink supplies which make use of low cost materials and are relatively easy to manufacture, thereby reducing ink supply cost that tends to reduce the per page printing costs. In addition, these ink containers should be volumetricly efficient to produce a relative compact ink supply for reducing the overall size of the printing system. In addition, these ink supplies should be capable of being made in different form factors so that the size of the printing system can be optimized. Finally, these ink supplies should be compatible with inks used in inkjet printing systems to prevent contamination of these inks. Contamination of the ink tends to reduce the life of the inkjet printhead as well as reduce the print quality.
One aspect of the present invention is an ink container for providing ink to an inkjet printhead. The ink container includes a reservoir for containing ink. Also included in the ink container is at least one continuous fiber defining a three dimensional porous member. The at least one continuous fiber is bonded to itself at points of contact to form a self-sustaining structure that is disposed within the reservoir for retaining ink. Ink is drawn from the self-sustaining structure and provided to the inkjet printhead.
In a preferred embodiment, the present invention the at least one continuous fiber is a bi-component fiber having a core material and a sheath material at least partially surrounding the core material. In this preferred embodiment the core material is polypropylene and the sheath material is polyethylene terephthalate. The at least one continuous fiber is preferably bonded to itself by heat that softens the fiber to bond to itself.